In a telecommunications central office or PBX (private branch exchange) the wires from telephones and other telecommunications apparatus are usually connected to the telecommunications lines by connector blocks which include a plurality of terminals to which the wires of the telecommunications apparatus are connected, the terminals also being connected to the telecommunications lines. Space is usually a major factor in any telecommunications installation, and it is desirable that the connecting block accommodate the intended number of terminals and connections within the smallest practicable volume. Many different connector blocks configurations are known, but are deficient or not wholly desirable in their construction or performance for many purposes, especially PBX systems and other office telecommunications systems in which relatively little space is available for the centralized telecommunications equipment including the associated connector blocks.